The invention relates to recycleable bulk bag containers having an exterior fabric layer and an interior fabric layer or interior film liner. Such containers are used in the storage and transport of materials in powder, granular, pellet, bead and other particulate form, such as chemicals, foodstuffs, cement and so forth. Such containers carry loads of up to one ton or more and desirably have a considerable safety margin above one ton.
In the art of transporting of dry, free-flowing bulk materials such as powders, granulars, and other particulates such as sugar, flour, plastic additives, mined ores or plastic molding powders, the use of bulk bags are well known to the industry, with such bags commonly having an upper receiving means for receiving contents within the bag. The bag is then transported after being filled and a lower discharge outlet which would be sealed during transport is opened into a receiving bin after transport, and the contents would be poured therefrom through the discharge outlet. In addition, fabric bulk bags may be required to have an inner polyethylene liner for moisture control, or contamination control, or to meet governmental requirements, such as food products that must be sealed within the polyethylene liner for purpose of purity as opposed to a plain fabric bag.
Bulk bag containers are frequently made from woven fabric, for example, woven polypropylene or another synthetic material. The woven fabric may be sealed by application of a coating layer of polypropylene or polyethylene. Bulk bag containers commonly have a plastic film liner of polyethylene inside the woven fabric layer of the bulk bag container. Bulk bag containers usually have lifting loops attached to the main body of the container, and points of attachment become regions of high stress. Similarly, seams between adjacent portions of the container become regions of high stress concentration, especially at lower portions of the container where there is an increased tendency of the woven fabric to elongate adjacent to the seams, and where seams do not tear, there is additional space which allows for powdery substances to leak through seams. This leakage presents environmental problems, cleanliness problems, product loss problems, dust explosion problems and breathing disorder problems for the user. Recycleability of bulk bag containers avoids environmental waste and the need to landfill the bulk bag after a single use.
Similarly, bulk bag containers made of woven polypropylene fabric and an interior polyethylene film liners present recycling problems due to the multiple plastic components. Such bulk bag containers need to have the liners seperated from the polypropylene fabric prior to recycling. Even after removal of the polyethylene liner from the bulk bag containers, portions of the polyethylene liner remain between seams of the bulk bag containers where the liner was stitched or sewn or glued into the bulk bag container. In addition, where glue is used to make a bulk bag, the glue can be a contaminant to the recycling process.
Another problem with bulk bag containers exists regarding stacking stability. When air is trapped within a sealed liner of a bulk bag, the bulk bag container becomes very unstable and will tip over. This instability occurs when both the fill spout and discharge spout of a bulk bag liner are sealed. The present invention overcomes the instability problems associated with air inside a sealed liner of a bulk bag container.
Attempts to overcome the leaking problems associated with bulk bag containers have focused on bulk bags with a polyethylene liner as disclosed in U.S. Pat. No. 4,946,291.
The problems addressed by this invention is the provision of a bulk bag container which is fully recycleable, leak proof to powdery substances, and stable when stacked.